1. Field of the Invention
The invention relates to a self-balancing means for brake shoes of caliper brakes to equalize essentially wear of brake linings, in particular for caliper brakes of disc brake assemblies designed to absorb large amounts of power.
2. Prior Art
In a caliper brake assembly for heavy-duty disc brakes, for example in logging or mining cable systems, or in heavy-duty winch systems, it is not unusual for brake linings of the brake shoes to wear unevenly, that is to wear to a greater extent adjacent one edge of the shoe when compared to the other. This results in an inwardly or outwardly tapered brake lining which, when the wear becomes excessive, requires premature lining replacement to avoid scratching the disc. Commonly, prematurely rejected worn linings which have been worn unevenly as above would have been capable of considerable additional use if the linings had worn evenly, that is if thickness of the brake linings adjacent inner and outer peripheries of the brake linings had been maintained generally equal as the shoes wear.
Theoretical analysis of brake lining wear characteristics is complex, and the rate of wear of a given lining material for a constant disc surface finish appears to depend mainly on pressure between the shoes and the disc, maximum temperature generated during brake application, and accumulated time of the brake application. One shoe and lining combination could be designed for a particular brake assembly to wear essentially evenly under one set of conditions, but when the same shoe and lining combination were used in another set of conditions, the lining could wear unevenly, thus necessitating the premature replacement as described above.
Furthermore, when the linings of a satisfactory combination of shoes and lining of a particular brake are replaced and the linings of claimed equivalent wear characteristics of a different manufacturer are substituted, it is often found that, with no other changes to the structure, rapid and uneven wear of the replacement linings results. To the inventor's knowledge, there are no devices available that ensure essentially equal wear of brake lining in all conditions irrespective of the material of the brake lining, pressure and temperature variations.